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P F Milner

Publications and source records attributed to P F Milner.

At least 55 records · Page 3Linked to original sources
PubMed1973

Erythrocyte Hb-S concentration. An important factor in the low oxygen affinity of blood in sickle cell anemia.

The blood in sickle cell anemia has a very low oxygen affinity and, although 2,3-diphosphoglycerate (2,3-DPG) is increased, there is doubt as to whether this is the only factor responsible. In this study of 15 patients with sickle cell anemia (Hb SS) no correlation was found between oxygen affinity (P(50) at pH 7.13) and 2,3-DPG in fresh venous blood. Whole populations of Hb SS erythrocytes were therefore separated, by an ultracentrifuge technique, into fractions of varying density. The packed red cell column was divided into three fractions; a bottom fraction rich in deformed cells or irreversibly sickled cells (ISC), with a very high mean corpuscular hemoglobin concentration (MCHC); a middle fraction containing cells with the highest content of fetal hemoglobin; and a top fraction containing reticulocytes and discoid cells but free of deformed cells. Oxygen affinity was shifted to the right in all layers (mean P(50) (pH 7.13)+/-1SD: top 46.3+/-2.9 mm Hg: middle 49.8+/-4.9 mm Hg; bottom 61.0+/-5.8 mm Hg) compared with normal blood (top 32.1+/-0.7 mm Hg: bottom 30.1+/-0.5 mm Hg). 2.3-DPG was increased in the top fraction, but was low or normal in the bottom fraction (top 21.8+/-3.4 mumol/g Hb: middle 17.7+/-2.2 mumol/g Hb; bottom 13.8+/-3.1 mumol/g Hb; normal whole blood 14.3+/-1.2 mumol/g Hb). The level of 2,3-DPG in top fractions could not account for the degree of right shift of P(50), and in the middle and bottom fractions the even greater right shifts were associated with lower levels of 2,3-DPG. Top fraction cells depleted of 2,3-DPG had a higher, but still abnormally low, oxygen affinity. A strong relationship was found between oxygen affinity and MCHC. The fractions with the greatest right shift in P(50) had the highest MCHC (top 32.4+/-2.0; middle 36.2+/-3.1; bottom 44.6+/-3.2 g/100 ml, respectively) and the plot of P(50) vs. MCHC showed a positive correlation (r = 0.90, P < 0.001). The red cell population in sickle cell anemia is not homogeneous but contains cells of widely varying Hb F content, 2,3-DPG, and hemoglobin concentration. Paradoxically, the cells with the lowest O(2) affinity have the lowest 2,3-DPG, but they also have the highest concentration of Hb S. The dense, deformed cell called the ISC is but the end stage in a process of membrane loss and consequent increase in hemoglobin concentration. The P(50) of Hb SS blood is, to a large extent, determined by the presence of these cells (r = 0.85, P < 0.001). Increased concentration of Hb S in the cell favors deoxygenation and crystallization even at relatively high P(o2). Lowered affinity for oxygen appears to be closely associated with Hb S concentration and not with 2,3-DPG content.

Adolescent↗
PubMed1973

Life span of carbamylated red cells in sickle cell anemia.

By using three isotopes of diisopropyl-phosphofluoridate ([(3)H]-, [(14)C]-, and [(32)P]DFP) simultaneously, the life span of red cells from 20 patients with sickle cell anemia (Hb SS) has been studied after varying degrees of carbamylation in vitro with cyanate (NCO) and carbamyl phosphate (CP). The results are expressed in terms of the red cell mean life span (MLS). The MLS of red cells in the patients studied averaged 15.2+/-6.3 (SD) days. After carbamylation the increase in red cell life span was linearly proportional to the concentration of cyanate used, so that at 0.01. 0.02, and 0.3 M NCO (approximately 1, 1.6, and 2 mol NCO/mol Hb) the average increase in MLS was 8.14+/-4.9 days, 14.7+/-4.1 days, and 18.4+/-8.8 days, respectively. Analysis of survival curves and the results of an experiment using a population of Hb SS cells separated by centrifugation indicated that carbamylation had a disproportionate effect on the survival of the youngest cells in the population. Improvement in MLS correlated with the reticulocyte count of the cells carbamylated. This finding is explained on the hypothesis that the life span of irreversibly sickled and other damaged cells is not improved by carbamylation but that carbamylation greatly improves the life span of the young, and as yet undamaged, cells. For this reason extracorporeal carbamylation is not favored as a form of therapy. At the level of carbamylation attainable by oral therapy, however, it would appear likely that only a modest increase in red cell life span will be achieved.

Adolescent↗
PubMed1968

Relatively benign sickle-cell anaemia in 60 patients aged over 30 in the West Indies.

A study in Jamaica of 60 patients with sickle-cell anaemia over the age of 30 years showed that most of them were in full-time employment. Pains in the bones or joints, leg ulceration, and jaundice were the most frequent types of presentation, but only two patients had a haemoglobin level consistently below 6 g./ 100 ml. Most of the patients were well developed and of average height, and, though the development of secondary sexual characteristics was delayed, there was an average of 2.6 pregnancies per patient. These findings suggest that the course is more benign than has been realized.

Adult↗